I believe your choise of AUX1 or AUX2 is correct for the receiver, but try all of the buttons and see.

I picked up the 15-1994 today. After I got it out of the box, I noticed something VERY strange...it has NO button for DVD! In the manual it states that Laser Disc (!) players are under the "VCR" catagory. So I tried programming my Pioneer DVD player as a vcr with the code in my Cinema 7 book. It worked just fine. In fact, the "Enter" (or is it Select?) button worked whereas I had to fix it on my cinema 7 using the advanced code.

The 15-1994 is definately an odd bird. I did use the 992 function to make AUX1 a VCR, and then give it the DVD code. However, I don't remember if I actually NEEDED to do that. BTW, the manual does NOT mention the 992 function! (even though it seems work :)